Adhesive composition and optical member using the same

Abstract

An adhesive composition includes 100 parts by weight of a (meth)acrylate copolymer having a weight average molecular weight of 1,000,000 to 2,000,000 g/mol; and 0.05 to 5 parts by weight of a carbodiimide cross-linking agent.

What is claimed is:  
     
       1. An adhesive composition, comprising:
 100 parts by weight of a (meth)acrylate copolymer having a weight average molecular weight of 1,000,000 to 2,000,000 g/mol; 
 0.05 to 5 parts by weight of a carbodiimide cross-linking agent; 
 0.05 to 5 parts by weight of an isocyanate cross-linking agent; and 
 greater than 0 to 1 parts by weight of a silane coupling agent, 
 wherein:
 the adhesive composition has an adhesive strength of 4 N/25 mm to 7 N/25 mm, 
 the adhesive composition has a gel content of 77 to 93%, and 
 
 further wherein said (meth)acrylate copolymer comprises:
 0 to 9 parts by weight of a carboxyl group containing monomer; 
 0.1 to 1.8 parts by weight of a hydroxyl group containing (meth)acrylic monomer, and 
 89.2 to 99.9 parts by weight of a (meth)acrylic acid ester monomer, the (meth)acrylic acid ester monomer including at least one of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n butyl (meth)acrylate, isobutyl (meth)acrylate, tert butyl (meth)acrylate, isoamyl (meth)acrylate, n hexyl (meth)acrylate, n heptyl (meth)acrylate, n octyl (meth)acrylate, tert octyl (meth)acrylate, 2 ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate and dodecyl (meth)acrylate. 
 
 
     
     
       2. The adhesive composition as claimed in  claim 1 , wherein said (meth)acrylate copolymer further comprises at least one of an epoxy group containing acrylic monomer, an amino group containing acrylic monomer, a phosphate group containing acrylic monomer, a sulfonic acid group containing acrylic monomer, a urethane group containing acrylic monomer, a phenyl group containing acrylic vinyl monomer, a silane group containing vinyl monomer, styrene, chlorostyrene, α-methylstyrene, vinyltoluene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, and vinyl pyridine. 
     
     
       3. The adhesive composition as claimed in  claim 1 , wherein said adhesive composition has a viscosity of 500 to 5,000 mPa·s at 25° C. 
     
     
       4. An optical member comprising an adhesive layer formed of the adhesive composition as claimed in  claim 1 . 
     
     
       5. The adhesive composition as claimed in  claim 1 , wherein the carbodiimide cross-linking agent includes at least one compound obtained by decarbonation condensation reaction of one or more of 4,4′-diphenylmethane diisocyanate, 3,3′-dimethoxy-4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-diphenylether diisocyanate, 3,3′-dimethyl-4,4′-diphenylether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, and tetramethyl xylene diisocyanate. 
     
     
       6. The adhesive composition as claimed in  claim 5 , wherein the isocyanate cross-linking agent includes a diisocyanate compound. 
     
     
       7. The adhesive composition as claimed in  claim 1 , wherein the adhesive composition includes 0.1 to 3 parts by weight of the carbodiimide cross-linking agent. 
     
     
       8. The adhesive composition as claimed in  claim 7 , wherein the adhesive composition includes 0.15 to 3 parts by weight of the isocyanate cross-linking agent. 
     
     
       9. The adhesive composition as claimed in  claim 1 , wherein a total amount of the carbodiimide and the isocyanate cross-linking agents in the adhesive composition is no greater than 4.3 parts by weight. 
     
     
       10. The adhesive composition as claimed in  claim 9 , wherein the total amount of the carbodiimide and the isocyanate cross-linking agents is from 0.3 to 4.3 parts by weight. 
     
     
       11. The adhesive composition as claimed in  claim 1 , wherein the adhesive composition comprises:
 0.05 to 5 parts by weight of the carbodiimide cross-linking agent; and 
 0.1 to 4 parts by weight of the isocyanate cross-linking agent. 
 
     
     
       12. An adhesive composition for adhering an optical member to a flat panel display, the adhesive composition comprising:
 100 parts by weight of a (meth)acrylate copolymer having a weight average molecular weight of 1,000,000 to 2,000,000 g/mol; 
 0.05 to 5 parts by weight of a carbodiimide cross-linking agent; 
 0.05 to 5 parts by weight of an isocyanate cross-linking agent; and 
 a silane coupling agent, the silane coupling agent being present in an amount of greater than 0 to 1 part by weight, 
 wherein:
 the adhesive composition has an adhesive strength of 4 N/25 mm to 7 N/25 mm, 
 the adhesive composition has a gel content of 77 to 93%, and further wherein said (meth)acrylate copolymer comprises: 
 0 to 9 parts by weight of a carboxyl group containing monomer; 
 0.1 to 1.8 parts by weight of a hydroxyl group containing (meth)acrylic monomer, and 
 89.2 to 99.9 parts by weight of a (meth)acrylic acid ester monomer, the (meth)acrylic acid ester monomer including at least one of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n butyl (meth)acrylate, isobutyl (meth)acrylate, tert butyl (meth)acrylate, isoamyl (meth)acrylate, n hexyl (meth)acrylate, n heptyl (meth)acrylate, n octyl (meth)acrylate, tert octyl (meth)acrylate, 2 ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate and dodecyl (meth)acrylate.